(above) Chile's President Sebastian Pinera, right, shakes hands with Mexico's President Felipe Calderon, left, as Colombia's President Juan Manuel Santos, center, looks on at the government palace in Lima, Peru, Thursday, April 28, 2011. Presidents of Chile, Mexico, and Colombia will meet with Peru's President Alan Garcia to discuss and possibly sign an agreement to establish commercial links with Asian countries of the Pacific region. (AP Photo/Martin Mejia)

LIMA, Peru (AP) -- The presidents of Mexico, Colombia, Chile and Peru signed an agreement Thursday expressing their commitment to pursue integration of their economies and a strengthening of trade links with the Asia-Pacific region.

The four leaders said the envisioned trade alliance - which Panama and Ecuador could possibly also join - would be the biggest trade zone in Latin America, surpassing the Mercosur common market of Brazil, Argentina, Uruguay and Paraguay.

"Our four nations, and Panama in the near future, represent 200 million people. Our countries account for 55 percent of Latin American exports," said Peruvian President Alan Garcia. "This is not a romantic integration, a poetic integration. It is a realistic integration with the world and to the world."

The agreement includes no concrete provisions, however, and has been described by officials of the four countries as merely "a roadmap."

Garcia said Chile, Colombia, Mexico and Peru are notable for their strong economic growth. In contrast to Mercosur in recent years, all four nations have been led by vigorous free-market defenders.

Mexican President Felipe Calderon said the four economies have a total combined value of $872 billion, compared to $543 billion for Mercosur. His foreign ministry said their combined exports also far exceed those of Mercosur, $443 billion against $282 billion.

But, Caldeorn added, the bloc will not be "just the sum of our exports and imports, it is a synergy of competitiveness."

Chilean President Sebastian Pinera said the Pacific Accord signed Thursday will not only liberalize trade in goods but trade in services and ease the movement of investment capital and financial integration.

Colombia's president, Juan Manuel Santos, said the new partnership was not a closed one. Its members will "welcome those countries that wish to join this process."